The present invention relates to a method of deploying non-destructive examination and/or support equipment for underwater inspection and repair of welds and mechanical structures in a nuclear reactor environment and particularly relates to the transportation and deployment of inspection and/or work tools in the underwater environment in any one of a nuclear reactor vessel, a spent fuel pool or an equipment pit at a nuclear reactor site.
Submerged welds and mechanical structures in a nuclear reactor environment such as the reactor vessel, a spent fuel pool or an equipment pit require periodic non-destructive examination to assess their structural integrity and repair if necessary in order to assure continued reliability and the performance of their functions. These examinations are normally conducted during outages when there is a high intensity of concurrent repair/modification work being performed in adjacent areas, often with very limited access. The non-destructive examination and support equipment for performing repair work may include for example various customized tooling fixtures, cameras, cable reels, push-pull devices, telescoping arms/assembles, hydraulic systems, vacuum hoses, eddy current probes and other equipment.
Equipment used to transport and position non-destructive examination equipment for examination of and work on submerged welds and other structures have included bridges, platforms and submersibles. Bridges and platforms have only a limited amount of work space with the result that tasks to be performed from them must often be done in series thereby extending overall plant outage durations. Also, when using a refueling bridge for inspection or other work, no such other activity is possible from the refueling bridge during fuel movement. Submersibles eliminate the need to use the bridge or platform for most tasks thus reducing scheduling conflicts and allowing work to be performed in parallel. However, submersibles have a high initial cost and tend to be costly and relatively complex from a maintenance perspective while managing their profile and delivery systems. Accordingly, there has developed a need for a method of delivering equipment to be used in the performance of underwater non-destructive examinations and repair work in a manner which precludes obstruction of or interference with other activities occurring in the vicinity of the examinations or repair, i.e., nuclear fuel movement, and provides versatility and capability for critical and non-critical path work in the reactor vessel, equipment pit and spent fuel pool.